The approaches described in this section are approaches that could be pursued, but not necessarily approaches that have been previously conceived or pursued. Therefore, unless otherwise indicated, it should not be assumed that any of the approaches described in this section qualify as prior art merely by virtue of their inclusion in this section.
Computers are very powerful tools for searching information. A search engine is a common mechanism that allows users to search for information using computers. A search engine accepts a search query as input. A search query is typically composed of one or more keywords and provides a search result as output. The search result identifies information that the search engine has determined “satisfies” the search query. Search engines often maintain an index of a corpus of information that allows the search engine to efficiently identify information in the corpus that satisfies a given search query.
One type of well-known search engine is an Internet search engine. Internet search engines are useful for searching semi-structured or unstructured data, such as the text content of a web page. However, the user interfaces of Internet search engines typically take a “one size fits all” approach with regard to how the user may scope the search. In particular, Internet search engines typically provide only a single text entry field into which the user enters one or more keywords. The Internet search engine then uses the entered keywords to identify information items that satisfy the entered keywords. This approach works well with the semi-structured and unstructured data that is indexed by Internet search engines, because such data typically is not represented by a highly-structured data model that is known to the user a priori the search. However, for highly structured data represented by a data model that the user has knowledge of prior to the search, the limited user interfaces provided by Internet search engines may be inadequate, inefficient, or cumbersome for users.